Self-propelled percussion tool assembly



Dec. 28, 1965 w, o sc 3,225,842

SELF-PROPELLED PERCUSSION TOOL ASSEMBLY Filed Jan. '7, 1963 3Sheets-Sheet 1 FIG.3 F|e.4

3 2 4 INVENTOR.

W. R. ROESCHEN I BY ATTORNEYS Dec. 28, 1965 w. R. ROESCHEN 3,225,842

SELF-PROPELLED PERCUSSION TOOL ASSEMBLY Filed Jan. '7, 1965 5Sheets-Sheet 2 INVENTOR.

W. R; ROESCHEN Q-OQUMQ A TTORNE Y5 Dec. 28, 1965 w. R. ROESCHEN3,225,842

SELF-PROPELLED PERCUSSION TOOL ASSEMBLY Filed Jan. '7, 1963 3Sheets-Sheet 3 DUMP vi? 350 SELECTOR VALVE 320 INVENTOR W R. ROESCHEN ATTORNE YS United States Patent Wisconsin Filed Jan. 7, 1963, Ser. No.249,851 Claims. (Cl. 173-24) The present invention relates to poweredpercussion tools of a type heretofore in use for a variety of purposes,such as the tamping of fills, cutting and breaking of pavements, drivingof posts and pilings, and the like, and has as an object the provisionof a novel and improved unitary organization of such a percussion toolcharacterized by high operative adaptablity and marked practicaladvantages.

There are two basic conditions which must be met in percussion toolconstruction which determine the design features necessary for suchequipment. Engineering tests have shown that when fracturing streetsurfaces, for example, a shear force must be generated which is greatenough to fracture the surface at every single blow. In so doing, thegenerating point of lateral shock waves is isolated when the surface isruptured, and beyond approximately ten feet from the point of impact,the resulting vibrations are of less than 3 mils amplitude and aredeemed to be within the danger to persons and danger to structures saferange. However, the vertical shock waves produced by the impact,referred to as displacement of the fill below the tool, are of seriousconsequence. These impact forces continue downward until compression ofthe underlying material resists and cancels out the imposed forces,i.e., until the impact tool meets a force sufficiently strong to stopits downward movement. Consequently, this displacement causes strain onexisting utilities lying below the surface being worked on by the tooldue to the pressures exerted on the pipe joints, changes of position,and scaling of old pipes and the like caused thereby. The damage may notbe noticeable immediately, but frequently early failure of suchutilities is a definite consequence of such vertical impact forces.Similar disadvantages are present when percussion tools are used for thetamping of earth fills. For example, if a utility has been placed in atrench and the tool is being used to tamp the earth fill, such verticalimpact forces may cause displacement of the utility and thereby damagethe same.

The present invention is directed to a precussion tool including anarrangement of hydraulic components which utilizes maximum shear forcesto cause complete fracture of a pavement, or complete tamping of anearth fill, through the average range of materials for each single blow;and, in addition thereto, incorporates a hydraulic dampening arrester inthe tool operating assembly to stop the impact tool as soon after thepoint of impact as the operator may determine to be required to preventdamage. Therefore, the arrangement of the present invention does notallow the tool to follow through and cause the vertical compression anddisplacement shock effects on existing or new utilities arranged belowthe tool assembly.

When installing new utilities, it is necessary to compact gently, andeffectively, the first foot of dirt directly over the new installation.In all cases, this is a highly critical job and when the dirt isback-filled into the trench, there may be an existing void or air pocketand protection must be guaranteed that the impact equipment will notfall through this void and damage the utility. Here again, the hydraulicdampening control of the percussion tool operating assembly allowsimpact at the proper level above 0 the utility with surety that thepercussion tool will not 7 fall through a void area and cause damage tothe utility.

In order to effectively use this stroke checking, it is necessary toprovide a means for vertical positioning of the tool since the strokethereof is limited. The percussion tool assembly of the presentinvention has incorporated a range of approximately 3 feet in verticaladjustment from the level so that the tool can reach the desired impactarea in coordination with the hydraulic dampening range. One of thesefeatures, i.e., the impact at the proper level and the verticalpositioning of the hammer tower, without the other would be valueless.

The percussion tool assembly in accordance with the present inventionhas many uses depending upon the type of tool employed. The tools may beeasily interchanged. The assembly may, for example, have a tool adaptedto. drive posts, pilings, and the like, in a usual manner and at variousangles of adjustment both with respect to a horizontal and a transverseplane. Alternatively, the assembly may be provided with a tool adaptedto serve as a chisel and the assembly applied to cut and trench throughpavements of diverse composition; with a tool adapted to serve as animpact nose and the assembly operated to crush and break pavements andother solid matter; with a tool adapted to serve as a tamping foot andthe assembly applied to pack and firm fills of loose materials. Apercusison tool of the type described is especially advantageous andeffective when joined with a motor vehicle for self-propulsion at ratesappropriate to move the tool from place to place along roads andhighways, and for alternative travel at very slow creeping speedssusceptible of correlation with the rate of tool operation.

It is an object of the instant invention to provide a practical andefficient unitary organization for the above purposes.

Other principle objects of the present invention are to provide a mobilevehicle upon which the percussion tool is pivotally mounted in avertical frame assembly which may be tilted with respect to thelongitudinal axis ofthe vehicle and with respect to the transversedirection thereof, to provide means for mounting various tool elementsin the vertical frame to drive posts, break concrete, etc., to providehydraulic means for raising and lowering the vertical frame carrying thepercussion tool with respect to the main frame, to raise and lower thetool with respect to the impact area, to adjust the frame laterally ofthe vehicle and maintain the frame in a desired horizontal position withrespect to the vehicle when the Wheels of the vehicle encounter unevenground, to tilt the vertical frame with respect to the longitudinal axisand transverse direction of the vehicle; and, to provide an improvedcontrol means for operation of said hydraulic means as desired.

These and other objects of the present invention will become evidentwith regard to the details of structure which are illustrated in theaccompanying drawings, wherein:

FIGURE 1 is a top plan view of a typical embodiment of the invention asarranged for practical use in one customary adjusted disposition of thepercussion tool assembly,

FIGURE 2 is a side elevation of the organization according to FIGURE 1,broken lines in the view indicating alternative positions to whichelements of the percussion tool assembly may be adjusted,

FIGURE 3 is a front-end elevation of the organization according toFIGURE 1 with the tool assembly in a lateral position of adjustmentdifferent from that proviously illustrated,

FIGURE 4 is a fragmentary, detailed segment of the assembly according toFIGURE 3 illustrating an alter native adjusted position of thepercussion tool assembly,

FIGURE 5 is a schematic drawing of the hydraulic control apparatus foroperating the various hydraulic means of the percussion tool assembly,

FIGURE 6 is a detailed view in longitudinal section of the lower end ofthe main hydraulic piston-cylinder assembly,

FIGURE 7 is a fragmentary, detailed view in vertical section taken alongsection line 77 in FIGURE 6, and

FIGURE 8 is a detailed view in vertical section taken substantiallyalong section line 88 in FIGURE 6.

In the organization of the improved percussion tool assembly of thepresent invention, as illustrated in FIG- URE 1, for example, a motorvehicle is arranged with the frame thereof including longitudinal bearermembers 10 and 10 being supported by rear wheels 11 and front wheels 13secured, respectively, to the rear axle 12 and the front axle 14. Aconventional motor 15 is provided to drive axle 12 and axle 14 throughgearing 16 and gearing 18, respectively, in two different speed ranges,one for highway travel and one for creeping during operation of thepercussion tool.

The conventional automotive drive for highway travel is schematicallyshown in FIGURE 1. This drive includes the motor 15 which drives atransfer case 20 through drive shaft 19. The transfer case may beadjusted in a conventional manner by lever 21 to apply power to thedrive shaft 23 for the front axle gearing 16 and/or the drive shaft 25for the rear axle gearing 18. Lever 22 is the gear-shift lever for thetransmission 17 of the motor 15. The transfer case also con tinuouslydrives hydraulic pump 300 which supplies a low pressure and a highpressure hydraulic fluid for controlling the position of the tool asdescribed in detail hereinafter.

The drive system as schematically described above is adequate and usefulfor propulsion of"themotor vehicles along roads and highways. However,steady advancement at very slow, creep speeds greatly contributes to theeffectiveness of the tool assembly for use in many operations, such asthe packing of trench fills, the scoring of pavements, the breaking ofpavements, and the like, and the speed ratios of conventional automotivetransmissions are inadequate to provide the steady, creeping advance ofthe carriage appropriate for effective correlation with operation of thetool assembly without damage to the conventional equipment. Hence, afeature of the instant invention is the association with theconventional automotive drive of an alternatively employable,supplementary transmission, available at the will of the operator, toapply power from the motor 15 for the provision of a creep drive.

The creep drive of the present tool utilizes gearing within theabove-described transfer case 20, drive shafts 23 and 25, and gear boxes16 and 18. A hydraulic creep motor provides an alternative power sourcefor the automotive drive gearing in the transfer case 20. This powersource is applied to the axles through the above-described drive shafts.Motor 30 is operated by low pressure hydraulic fluid supplied from pump300 (see FIGURE 5). Pump 300 is operative at all times with motor 15.

The percussion tool assembly of the present invention is mounted uponthe powered vehicle described above by longitudinally extending framemembers 52 and 53 pivotally secured in spaced parallel relationship tothe opposite frame members 10 and 10' of the motor vehicle by means ofbrackets 54 and 55, note FIGURE 2, which are rigidly provided on theframe. The frame members 52 and 53 extend outwardly of the carriage forthe motor vehicle and project beyond the end of the frame adjacent theaxle 14. In the upper and outer ends of the frame members 52 and 53 arefixedly mounted aligned bearings 52, for example, see FIGURE 3, withinwhich a shaft 56 is journaled. Shaft 56 spans the frame members 52 and53 transversely of the vehicle at their outer ends, Brackets 58 whichare journaled on shaft 56 pivotally support the frame assembly of thepercussion tool assembly, generally indicated by numeral 60, on thisshaft.

The frame assembly 60 includes a vertical guide tower or frame 61 forthe percussion tool the frame being slidably supported for horizontalmovement on the two angle irons 62 arranged one above the other andforming tracks for displacement of the frame 61 transversely of thevehicle. The angle irons 62 are secured in spaced relationship by thebrackets 58 and by additional brackets 64. End pieces 66 also aid insecuring the angle irons 62 in spaced relationship and provide limitstops for the transverse movement of the vertical frame 61 along thetracks formed by the angle irons.

The vertical frame 61 is supported on the angle irons 62 by a rigidbox-like frame member 102 which partially surrounds the angle irons 62and has rollers 104 and 105 journaled therein and engaging the angleiron tracks. The frame member 102 is adapted to be moved along thetracks formed by members 62 by a hydraulic motor means 210 as describedin detail hereinafter. A rigid plate 106 is pivotally secured to theframe 102 by a pivot means 108. This plate 106 pivotally supports thevertical frame 61 which includes two U-shaped arms 109 and 110, whichare secured to plate 106, and spaced upright vertical posts 112 whichform the guide means for the tool and its weight 114 and are secured toarms 109 and 110. The percussion tool includes heavy weight 114 whichslides along the upright posts 112 and a tool 120 removably secured tothe weight. A lower U-shaped arm member 118 secures the bottom ends ofthe two posts 112 together and protects the weight 114 and the tool 120.

The weight 114 together with the tool 120, is raised and lowered along apath determined by the position of the upright posts 112 by means of apulley and cable system including pulley 154 secured to the upper end ofthe post 112 and a multiple sheave arrangement 156, 156'. The multiplesheave arrangement is used to raise and lower the weight by means ofcable 152 through the action of a main piston-cylinder assemblyincluding cylinder and piston rod 176 which is described in detailhereinbelow with reference to FIGURES 5, 6, 7, and 8. The cylinder 175and the pulley system are secured to and supported by the plate 106 byconventional bracket means as illustrated in FIGURE 2. The weight 114has guide grooves formed therein which partially surround posts 112 tomaintain the same in proper position.

As mentioned above, the tool assembly 61 may be adjusted with respect tothe motor vehicle in various manners. For instance, the tool assemblymay be moved transversely of the motor vehicle along tracks 62; thepercussion tool assembly may be laid back over the motor vehicle bypivoting about axis 56 as indicated in dotted lines in FIGURE 2 in orderto place the same in position for travel along roads and highways; thepercussion tool may be tilted about a longitudinal axis 108' of thevehicle as illustrated in FIGURE 4; and the entire percussion toolassembly may also be raised and lowered with respect to the horizontalby pivoting about the axis where frame member 52 and member 53 arejoined to the brackets 54 and 55 as illustrated by dotted lines inFIGURE 2. The various movements allow many uses of the tool withoutmoving the vehicle.

The lay-back of the percussion tool assembly over the motor vehicle fortravel which is illustrated by the dotted lines in FIGURE 2 isaccomplished by piston-cylinder assembly 220 which is pivotally securedto the frame member 52 by a bracket 222 and to one of the members 58separating the angle irons 62 by brackets 224. Hydraulic fluid issupplied to a respective side of the piston to expand or retract thesame and pivot the support assembly 60 about axis 56 of the shaft 56.Hydraulic pressure fluid is supplied the cylinder-piston assembly 220from a hydraulic system including the pump 30f} operated by motor 15 asdesc ib d in detail ftstz Hydraulic motor 210 propels the vertical frame61 transversely of the vehicle by means of the rollers 104 and 105'which track along angle irons 62. The hydraulic motor 210 drives agearing system 212 which meshes with gear rack 214 secured to the framemembers 58 and 64. This hydraulic motor 210 also is controlled by theabove mentioned hydraulic system described in detail hereinafter.

Tilting of the percussion tool assembly about a longitudinal axis of thevehicle, as illustrated in FIGURE 4, is accomplished by piston-cylinderassembly 230, which is pivotally secured to the box frame 102 and to thearm member 110. Expansion of the hydraulic cylinder-piston assemblypivots the plate 106, and therewith vertical frame 61 which is supportedthereby, about the axis 108 of journal 108. Pins 111 projectingforwardly from the plate 106 limit the degree of pivoting.

Raising and lowering of the percussion tool assembly 60 vertically withrespect to the ground is accomplished by pivoting the frame members 52and 53 about the pivot points of their respective supporting brackets 54and 55. Pivoting of the frame members 52 and 53 is accomplished by apair of piston-cylinder assemblies 250 and 251 which are pivotallyconnected to the vehicle frame by brackets 254 and 255, respectively.Each assembly 250 and 251 is also pivotally secured, respectively, toone of the frame members 52 and 53 by brackets 252 and 253. Actuation ofthe piston-cylinder assemblies likewise is controlled by the hydrauliccontrol system described in detail hereinafter. This actuation raisesand lowers the tool assembly 60 vertically with respect to the ground inan arc determined by the length of the frame members 52 and 53 and theirpivot points at the brackets 54 and 55, respectively. The vertical frame61, however, may be maintained in its vertical position by acorresponding compensating actuation of piston-cylinder assembly 220.

The hydraulic system for operating the various pistoncylinder units ofthe percussion tool assembly and for operating the main lift cylinder175 is illustrated in detail by FIGURE 5. The system as illustrated inFIGURE includes three main valves including a selector valve 320, a dumpvalve 350 and a sensing valve 380 including accumulator 395 and anauxiliary valve bank 200 including six auxiliary valves 201-206.Auxiliary valves 201 through 204, respectively, control operation of thepistoncylinder assemblies 251, 250, 230, and 220 for the positioning ofthe tool assembly 60 as described hereinabove. Auxiliary valves 205 and206, respectively, control operation of the hydraulic motors 30 and 210for the purposes described hereinabove.

The valves 201-206 are conventional Vickers spool valves having acentral, neutral position and two outlets. The first four double throwvalves, which are used to supply hydraulic fluid under pressure from thepump system 300 to either side of the pistons of each piston-cylinderassembly 220, 230, 250 and 251, operate by extending or retracting theselected pistons and the last two valves are for supplying fluid to thehydraulic motors 30 and 210 for operation thereof in either direction ina conventional manner. Operation of the individual cylinder-pistonassemblies for positioning of the percussion tool assembly 60 is amanual operation. The engine driven pump assembly 300 includes a lowpressure pump 301 and a high pressure pump 302 operating, respectively,at approximately gallons per minute and 25 gallons per minute. Operationof the hydraulic motor and piston-cylinder units is accomplished by thelow pressure pump 301. The high pressure pump 302 is used to operate themain lift cylinder assembly.

The operation of the several auxiliary valves is identical. Assuming forpurposes of illustration, it is desired to extend the piston ofcylinder-piston assembly 251, it is necessary to supply hydraulic fluidfrom pump 301 through auxiliary valve 201 of the valve bank 200 and line207 to the lower side of the piston. This hydraulic fluid raises orextends the piston, forcing the fluid above the piston through line 208,the auxiliary valve bank 200 and thence through return line 310, line311 or line 313 and relief valve 312 and line 314 to the sump 315 forthe pump system 300. This fluid in flowing to the sump 315 may be passedthrough a filter 316.

The main lift cylinder 175 may be operated either manually orautomatically by hydraulic fluid from high pressure pump 302 controlledby the system illustrated in FIGURE 5. As shown, the selector valve 320which determines the type of operation is in its neutral position. Inthis position, the oil is trapped behind the piston of the lift cylinderto hold the tool in a fixed position while the oil from the highpressure pump 302 is bypassed by selector valve 320 from line 321through chamher. 322 to line 322 which is, in turn, connected to thesump tank 315 for the pump system 300. When the selector valve 320is inthe neutral position, the oil trapped in the lift cylinder is blocked byfour valves. The valves are (a) the selector valve 320 where the oil inchamber 323 cannot escape into line 322' unless the selector valve spool330 is purposely shifted; (b) check valve 340; (c) the main relief valve345 which only will open ifthe main lift cylinder pressure exceeds apreset value greater than that required to hold the weight 114 and tool120 in a fixed position; and (d) the dump valve 350 which only opens onautomatic cycle.

In order to lower the tool 120 at a controlled rate, the selector valvespool 330 is shifted to the left, as illustrated in FIGURE 5; by thethrow-arm assembly 325: This opens chamber 323 to line 322 closing thevalve mentioned under (a) above. In order to raise the tool 120 at acontrolled rate, the selector spool 330 is moved to the right to blockpassage of oil from line 321 to line 322. The flow path is then throughlines 326, 352 and 400. Control of the raising speed can be achievedover a portion of the stroke of spool 330 since the flow from the highpressure pump 302 can be split by the degree of orificing between line321 and line 322. The flow not passing from line 321 to line 322 will,of course, pass through check valve 340, line 326, across the mainrelief valve 345 to the sensing valve 380, and through lines 352, 391and check valve 390 into the supply line 400 for the main lift cylinder175. Timing valve 410 would be closed during manual operation.

Manual lowering of the lift cylinder piston is accomplished by shiftingthe selector valve to allow dum ing from line 323' to line 322'. Theflow of fluid from the main lift cylinder 175 through line 400, forcingspool 406 to the left, line 352, line 323', chamber 323 and line 322 tosump 315.

The hydraulic system may also be operated on an automatic cycle which isinitiated by moving the selector valve spool 330 to the right tocompletely block line 321. This movement also blocks line 311 andexhaust flow from the low pressure pump 301 in line 310 is forced backthrough line 313, back passage pressure relief valve 312 and line 381'creating a pilot pressure in passages 381 and 334 of the sensing valve380. It is noted that the back pressure relief valve 312 is by-passed byline 311 in all other selector valve spool positions. This is done toinsure against inadvertent opening of the dump valve 350 when not onautomatic cycle.

During the up-stroke of the main lift piston rod 17 6 on automaticcycle, all of the oil from the main pump 302 passes through check valve340 across the relief valve 345 to the sensing valve 380, through checkvalve 390 and into supply line 400 for the lift cylinder. A smallportion of this oil will pass through line 411 to the timing valve 410,check valve 420, and line 388 to the cavity 404 above the spring-biasedaccumulator spool 405. This means that the accumulator spool 405 will bemoving downward during the up-stroke of the lift cylinder piston rod176. The speed of spool 405 will be determined by the setting of thetiming valve 410, which is a flow control needle valve adjustable fromapproximately to 1 gallons per minute.

During the first portion of the accumulator spool travel, line 353leading to the chamber behind the dump valve spool 360 is open to thesump tank for the pump system 300 because the passage between chambers396 and 389 of the accumulator 395 remains open and because chamber 389is in turn connected to line 385 which is in turn open to line 386 whichis always open to the sump tank through the drain 402. After theaccumulator spool 405 moves this first portion of its travel, chamber389 is blocked and the oil in line 353 between chamber 396 and the dampvalve spool 360 is trapped. When the accumulator spool 405 has movedfurther, chamber 396 is opened to chamber 397 so that pilot pressurefluid is admitted behind the dump valve spool 360. This in turn startsthe dump valve spool 360 moving to the right at a controlled rate ofspeed determined by the size of the orifice at the entrance to chamber397. As the dump valve 350 opens, a continuously increasing portion ofthe high pressure fluid is diverted from line 352 to line 351 and thepressure in the lift cylinder 175 is reduced at a controlled rate. Drain354 removes fluid from behind spool 360.

If the pressure behind the lift cylinder piston rod 176 is releasedalmost instantaneously the following sequence of events occur. The liftcylinder reverses instantaneously and retracts a short distance where itwill pause momentarily. The weight 114, however, continues to moveupward for a short time before coming to rest. At this time, there isslack in the cable supporting the weight 114. The tool then falls andtakes up the slack in the cable with a high impact on the cylinder. Thissequence of events happens very fast so that the slack in the cable isactually not apparent, but the situation occurs and creates severestructural loads during release. This is similar to the loads thatresult when a large press is decompressed without proper valving. Thearrangement of the hydraulic control system described herein eliminatesthis situation by controlling the rate of decompression and by keepingthe lift cylinder moving during the time that the weights and tools aredeaccelerating.

Until the weight 114 comes to rest and starts to fall, the reset spool406 remains in its spring offset position, as shown. As soon as theweights begin to fall, however, oil will begin to flow out of the liftcylinder. Since this oil cannot flow through check valve 390, it willpush the reset spool 406 back against spring 416. Before line 400 isfully open to line 352, line 385 becomes blocked and subsequently opento line 384. This means that there will be unrestricted pilot pressureat chamber 389 as long as there is an opening between lines 400 and 352.

Line 387 opens to line 386 when chamber 389 becomes pressurized. Theaccumulator spool 405 then begins to return. Note that the accumulatorspool 405 cannot begin to reset prior to this time because check valve420 prevents a back-flow to the main lift cylinder line 400 when thepressure in that line falls during acceleration. The accumulator spool405 takes a very short time to reset after line 387 opens to line 386.This means that chamber 396 will open to chamber 389 is an extremelyshort time since chamber 389 is now open to unrestricted pilot pressure.This, in turn, will move the dump valve spool 360 to the wide-openposition in this short time at which time oil is flowing out of the liftcylinder 175 as the tool 120 is accelerating downwardly.

During the downward stroke of the tool 120, the reset spool 406 willmove continuously due to the ever-increasing rate of flow passing out ofthe lift cylinder 175. However, as soon as the tool 120 hits bottom andthe flow from the lift cylinder stops, the reset spool 406 willimmediately return to its spring offset position where the oil behindthe dump valve spool 360 in line 353 is released due to the fact thatchamber 389 is reopened to drain through e 386. Re easing the oil fromline 353 will, of course, allow the dump valve 350 to close and startthe cycle over again by starting the up-stroke of the piston rod 176 forthe main lift cylinder 175.

As mentioned heretofore, in order to control the vertical shock forcesof the tool at the point of working, an adjustable hydraulic dampeningarrester has been incorporated into the main lift cylinder 175 to bringthe impact forces and the movement of the tool to a complete stop assoon after entering the point of impact as the operator may determine touse. This hydraulic dampening arrester is illustrated in detail byFIGURES, 6, 7, and 8.

The arrester is incorporated into the lower end of the main liftcylinder and includes the extended lower end 192 of the cylinder whichhas a cross-sectional area smaller than that of the main cylinder 175.The reduced lower end 192 is provided with a restricted by-passagechannel 177 which due to its restricted area cushions the fall of thepiston. Piston rod 176 has an enlarged main piston area 180 whichcorresponds essentially to the diameter of the main portion of thecylinder 17 5 and is sealed with respect thereto. The lower reduced endof the piston, which is secured to the area 180, however, correspondsessentially in diameter to the extended end portion 192 of reduced areain the cylinder 17 5 and is sealed with respect thereto at the bottomend of the down-stroke for the piston rod 176. As the piston rod 176passes downwardly in the cylinder 175, hydraulic fluid is forced out ofopening 178 in the lower reduced end 192 thereof and into line 400 ofthe hydraulic system, as previously explained with reference to FIGURE5. The opening 178 is of relatively large cross-sectional area andprovides a rapid flow of hydraulic fluid from the cylinder into thehydraulic system of FIGURE 5. As the piston approaches the end of itsstroke, however, the lower reduced end 190 of the piston passes into thecylinder portion 192 which is of reduced area and thus gradually cutsoff the direct outward flow of the exhausting fluid. Hydraulic fluid isthereby trapped in the annulus 191 defined between the reduced end ofthe piston 190 and the outer wall of cylinder 175. This trappedhydraulic fluid is utilized to cushion the downstroke of the piston 176.The hydraulic fluid trapped in annulus 191 is removed through restrictedpassage 177 which communicates through other passages with opening 173.

In order to provide for adjustment of the cushioning means, anadjustable needle valve 199 is incorporated in the restricted escapepassage leading from the annulus 191. As shown in FIGS. 6, 7 and 8 ofthe drawing, the restricted escape passage 177 extends verticallydownward to a horizontal passage 181 that leads outward to the needlevalve 199. The escaping fluid flowing in these passages passes throughan orifice 194 that cooperates with and is controlled by the needlevalve 199. From the controlled orifice 194, the fluid flows throughhorizontal passages 179 and 183 into the reduced end portion 192 of thecylinder 175 from whence it escapes through the opening 178 into theline 400 of the hydraulic system. -By adjusting the needle valve 199 inor out of the orifice 194, the effective area of the restricted passagemay be varied and consequently the rate of the return flow of thehydraulic fluid trapped beneath the piston 180 may be regulated tocontrol the timing of the stroke cushioning action.

At the start of the next upstroke of the piston 176, hydraulic pressurefluid is admitted through the line 400 and the opening 178 into thereduced lower end 192 of the cylinder 175 to exert force upward upon thereduced end of the piston 190. While the reduced end of the piston 190remains in the reduced cylinder end portion 192, some of the hydraulicpressure fluid flows through the restricted passage into the annulus191. In order that this return flow of the fluid may not beunnecessarily restricted by the needle valve 199, a check valve 195 isarranged in P e circuit relationship with the needle valve 199 to bypassit. By reason of this by-pass, the fluid may flow through the passages183 and 179 and then directly through the check valve 195 and thepassages 181 and 177 into the annulus 191. In this manner the annulus191 is quickly filled with hydraulic fiuid bypassed through the checkvalve 195 as the piston end 190 is pushed upward out of the lowerreduced cylinder portion 192 by action of the fluid pressure.

By this arrangement of the hydraulic system, the downward movement ofthe impact tool may be arrested at any predetermined distance below thepoint of impact that may be appropriate to prevent damage to underlyingstructures and the like. This is accomplished by adjusting the length ofthe cable 152 to cause the checking action of the reduced cylinder end192 to occur at a selected position of the impact tool relative to theguide tower 61 and then positioning the tower at the proper elevation toprovide for the desired impact While limiting further movement orfollow-through of the tool by the arresting action.

From the foregoing description and explanation of the operation of animproved self-propelled percussion tool apparatus constituting thepresently preferred embodiment of the invention, it will be readilyapparent that there has been provided an improved power drivenpercussion tool of the type used in the tarnping of fills, cutting andbreaking of pavements, driving of posts and piles, and the like which ischaracterized by high operative adaptability and improved practicaladvantages.

While a single embodiment of apparatus illustrative of the invention hasbeen set forth in detail by way of a full disclosure of a practicaloperating machine constructed in accordance with the invention, it is tobe understood that the invention is not limited to this particularembodying structure which is susceptible of many changes andmodifications by persons skilled in the art within the spirit of theinvention and therefore the invention is not to be limited to thedetails of construct-ion shown and described herein but covers all suchchanges and modificatrons as are emcompassed within the scope of thesubjoined claims.

The invention having now been fully set forth and explained, I claim asmy invention:

1. In a percussion tool unit comprising a powered, selfpropelledcarriage adapted for operation in two speed ranges, respectively, fortravel on highways at moderate speeds and for creep travel when theunits is in operation, and percussion tool means carried by saidself-propelled carriage, the improvement comprising a frame assembly forsupporting said tool means on said carriage including vertical framemeans for guiding said tool means in vertical movements and horizontalmovements transversely of said carriage and for tilting thereof about afirst axis extending transversely of said carriage, said vertical framemeans including vertical support means for guiding said tool meansduring vertical movements thereof,

track means extending transversely of said carriage, and means forsecuring said vertical support means to said track means for movementthereof along said track meansand for pivoting about a second axisextending longitudinally of said carriage, said frame asembly furtherincluding means securing said vertical frame means to said carriage,said last-mentioned means being pivotally secured to said carriage forpivoting about a third axis extending transversely of said carriagewhereby said vertical frame means may be raised and lowered with respectto said carriage and also being pivotally secured to said vertical framemeans to form said first axis ex- 10 tending transversely of saidcarriage whereby said vertical frame means may be laid back over saidcarriage, and

hydraulic means for adjusting said tool means and vertical frame meansin the various positions thereof with respect to said carriage includinga source of hydraulic pressure fluid,

first hydraulic means for moving said vertical support means along saidtrack means, second hydraulic means for pivoting said vertical framemeans about said first axis, third hydraulic means for pivoting saidvertical frame means about said third axis, and fourth hydraulic meansfor pivoting said vertical support means about said second axis, saidfirst, second, third, and fourth hydraulic means being operativelyconnected to said hydraulic pressure fluid source,

a main lift piston-cylinder hydraulic unit for raising-and lowering saidtool means in said vertical support means during each working strokethereof, a hydraulic damping arrestor and buffer means in one end ofsaid main lift piston-cylinder hydraulic unit for controlling the impactforces of said tool means at the impact end of a stroke of said toolmeans,

means operatively connecting said main lift unit to said hydraulicpressure fluid source, and

control means in said last-mentioned means for controlling operation ofsaid main lift unit to perform said working strokes thereof 2. A unit asdefined in claim 1, wherein said track means includes a pair of angleirons extending transversely of said carriage and spaced a distance infront thereof, and wherein said means for securing said vertical supportmeans to said track means includes roller means adapted to track alongsaid angle irons, and wherein said first hydraulic means includes areversible hydraulic motor secured to said means for securing saidvertical support means and said track means and operatively connected tosaid hydraulic pressure fluid source, gear means operated by said motorand gear rack means secured to said track means, said gear means meshingwith said gear rack means.

3. A unit as definedin claim 2, wherein said means for securing saidvertical support means to said track means further includes a framepartially surrounding said roller means and a plate secured thereto forpivoting about an axis constituting said second axis, said verticalsupport means being secured to said plate, and wherein said fourthhydraulic meansincludes a hydraulic pistoncylinder unit pivotallysecured to both said frame and said plate and operatively connected withsaid hydraulic pressure fiuid source forpivoting said plate relative tosaid frame about said second axis.

4. In a self-powered percussion tool unit comprising a powered,self-propelled carriage adapted for operation in two speed ranges,respectively, for travel on highways atmoderate speeds and for creeptravel when the unit is in operation, and percussion tool means carriedby said self-propelled carriage, the improvement comprising a frameassembly for supporting said tool means on said carriage including avertical frame means for guiding said tool means in vertical movementsand horizontal movements transversely of said carriage and for tiltingthereof about a first axis extending transversely of said carriage, andmeans securing said vertical frame means to send carriage for pivotalmovement about a second axis extending transversely of said carriagewhereby said vertical frame means may be raised and lowered with respectto said carriage, said securing means being pivotally connected to saidvertical frame means to form said first axis extending transversely ofsaid carriage whereby said vertical frame means may be laid back oversaid carriage, said vertical frame means including vertical supportmeans for guiding said tool means during vertical movement thereof, saidmeans securing said vertical frame means including means for supportingsaid vertical support means for horizontal movement thereof transverselyof said carriage and for pivotal movement thereof about a third axisextending longitudinally of said carriage, and hydraulic means foradjusting said tool means and vertical frame means in the variouspositions about said pivot axes and transversely of said carriage, amain lift piston-cylinder hydraulic unit for raising and lowering saidtool means in said vertical support means during each working strokethereof, a hydraulic damping arrestor included in one end of said mainlift pistoncylinder hydraulic unit and including a variable controlmeans to allow the impact forces and movements of the tool means to cometo a complete stop at a control point after the point of impact, andcontrol means for operating said main lift unit to perform said workingstrokes thereof.

5. A unit as difined in claim 4, wherein said hydraulic means foradjusting said tool means and vertical frame means in the variouspositions thereof includes a source of hydraulic pressure fluid,separate hydraulically operated means operatively connected to saidsource for moving said vertical support means horizontally transverselyof said carriage, for pivoting said vertical frame means about saidfirst axis, for pivoting of said vertical frame means about said secondaxis, and for pivoting said vertical support means about said thirdaxis, and first means for operatively connecting said main lift unit tosaid source of pressure fluid.

6. A unit as defined in claim 5, wherein said means for operating saidmain lift unit includes a selector valve arranged in said first meansfor controlling the connection of said main lift unit to said source,said selector valve having three basic valve positions corresponding tomanual exhaust of said main lift unit, manual lift of said main liftunit and automatic operation of said main lift unit, said selector valveincluding means for varying the speed of manual lifting and exhaustingof said main lift unit, a dump valve controlled by a pilot pressuredrawn from said source, said dump valve being operative only duringautomatic operation of said main lift unit to allow exhausting thereof,control means for said dump valve including second means operativelyconnecting said dump valve to said pilot pressure when said selectorvalve is in the automatic valve position thereof, and sensing valvemeans including a first valve operatively arranged in said first meansfor sensing exhaust flow from said main lift unit, means for by-passingpressure fluid through said first valve from said source to said mainlift unit during lift thereof, an accumulator valve in said secondmeans, and third means operatively connecting said accumulator valve tosaid first means for applying pressure from said first means againstsaid accumulator valve to control the position of the same and therebycontrol the application of said pilot pressure against said dump valveand exhaust of said main lift unit, and wherein said means for adjustingthe rate of said strokes includes timing valve means in said third meansfor regulating the pressure applied against said accumulator valve fromsaid first means and thereby the speed at which said accumulator valveadjusts and the rate of the stroke of said main lift unit.

7. In a percussion tool apparatus for impacting a surface being worked,a vehicle chassis, a source of power mounted on said vehicle chassis, agenerally vertical guide tower adjustably carried by said chassis, apercussion tool slidably mounted in said vertical guide tower in manneradapted to impact upon the surface being worked in performing a tampingoperation or the like, a hydraulic actuator mounted on said guide tower,power transmitting apparatus operatively interconnecting said hydraulicactuator on said tower with said percussion tool slidably mounted insaid tower in manner to effect reciprocation by said actuator of saidtool in said tower through a stroke of predetermined length, a hydraulicbuffer incorporated in said hydraulic actuator and operative thereon inmanner to check and cushion the downward stroke of said tool at thelower end of its sliding movement in said guide tower, a hydraulic powersystem operatively connected to said source of power in manner to bedriven thereby and connected to said hydraulic actuator to drive it, andmeans to adjust the vertical position of said adjustably carried towerrelative to said vehicle chassis, whereby said tower may be positionedvertically at an elevation to cause said tool to impact upon the surfacebeing worked prior to reaching the cushioned lower end of its stroke,said tool being checked and cushioned in its downward movement by saidhydraulic buffer upon penetrating below the surface being worked at thepoint of impact thereon.

8. In a mobile percussion tool apparatus, a vehicle chassis including asource of power, a generally vertical guide tower movably carried bysaid chassis for adjustment relative thereto in positioning its lowerend in desired operative relationship with a surface to be worked uponby said percussion tool apparatus, a weighted percussion tool slidablymounted in said vertical guide tower in manner adapted to impinge uponthe surface being worked, a hydraulic cylinder mounted on said guidetower for adjusting movement therewith, a piston and piston rodoperating in said hydraulic cylinder on said tower, a pulley and cablepower transmitting apparatus operatively interconnecting said piston rodand said slidably mounted percussion tool in such manner that when saidpiston rod is extended from said cylinder said percussion tool is raisedin said vertical guide tower, a hydraulic power and control systemoperatively interconnecting said source of power and said hydrauliccylinder in manner to provide for controlled actuation of said pistonrod, a hydraulic buffer system incoporated in said hydraulic cylinderand operating to check and cushion the retracting movement of saidpiston in said cylinder as said percussion tool drops to the lower endof said guide tower, and power operated adjusting means connected tosaid source of power in manner to be driven thereby and connecting tosaid movably mounted guide tower in manner to adjust the position of thelower end of said tower relative to the surface being worked, thearrangement being such that said guide tower may be positionedvertically in such manner that said percussion tool will impinge uponthe surface being worked prior to dropping to the lower point at whichthe retracting movement of said piston rod is checked and cushioned,whereby immediately after said percussion tool impinges upon the surfacebeing worked further downward movement or penetration of said tool willbe checked and cushioned by operation of said hydraulic buffer system toprevent excessive follow-through and undesired penetration of said toolbelow the surface being worked.

9. A mobile percussion tool apparatus comprising a vehicle chassisincluding a source of power and a hydraulic actuating and control systemoperatively connected to and driven by said source of power, apercussion tool carrying structure mounted on said vehicle chassisincluding a pair of spaced parallel supporting arms extendinglongitudinally of and projecting at one end of said chassis, meanspivotally connecting the proximal ends of said arms to said chassis forpivotal movement in vertical planes, a generally vertical tool guidingtower adjustably connected to the projecting distal ends of saidpivotally mounted arms for vertical movement therewith when said armsare pivoted, a weighted percussion tool slidably mounted in saidvertical guide tower and operatively connected to a main liftpiston-cylinder hydraulic unit of said hydraulic actuating and controlsystem for lifting and dropping thereby, a hydraulic damping arrestorand buffer means in said main lift piston-cylinder hydraulic unit forcontrolling the impact forces of said percussion tool at the impact endof a stroke of said tool, hydraulically actuated lifting means connectedto said pivotally mounted arms and operatively connected to saidactuating and control system in manner to provide for controlled raisingand lowering of said tool guiding tower, and means to adjust theposition of said tower on the ends of said vertically movable arms todirect said percussion tool in dropping upon a surface being worked.

10. In a mobile percussion tool apparatus, a power driven carriage, atransverse horizontal trackway movably mounted at one end of saidcarriage, power driven means operatively connected to raise or lowersaid horizontal trackway bodily relative to said carriage, a framemember slidably mounted on said movable trackway for movement therealongtransversely of said carriage, a vertically disposed guideway pivotallymounted on said frame member for tilting movement about an axis disposedlongitudinally of said carriage, and a percussion tool slidably mountedin said vertically disposed guideway for reciprocatory impactingoperation therein, the arrangement being such that said tool guidewaymay be raised or lowered relative to said carriage by operation of saidpower driven trackway raising or lowering means and may be traversedtransversely of said carriage and tilted in its transverse plane toposition it for guiding said percussion tool in impacting a surfacebeing worked, a hydraulic actuator for said percussion tool, and avariably controlled hydraulic buffer at one end of said actuator tocontrol movement of said percussion tool after impactv References Citedby the Examiner UNITED STATES PATENTS OTHER REFERENCES Arrow:Side-Action Mobile Hydraulic Hammer, Advertising Circular of Arrow Mfg.Co., 4 pp., received in United States Patent Ofiice, October 29, 1962.

BROUGHTON G, DURHAM, Primary Examiner,

D. FAULCONER, LAWRENCE P. KESSLER,

Assistant Examiners.

10. IN A MOBILE PERCUSSION TOOL APPARATUS, A POWER DRIVEN CARRIAGE, ATRANSVERSE HORIZONTAL TRACKWAY MOVABLY MOUNTED AT ONE END OF SAIDCARRIAGE, POWER DRIVEN MEANS OPERATIVELY CONNECTD TO RAISE OR LOWER SAIDHORIZONTAL TRACKWAY BODILY RELATIVE TO SAID CARRIAGE, A FRAME MEMBERSLIDABLY MOUNTED ON SAID MOVABLE TRACKWAY FOR MOVEMENT THEREALONGTRANSVERSELY OF SAID CARRIAGE, A VERTICALLY DISPOSED GUIDEWAY PIVOTALLYMOUNTED ON SAID FRAME MEMBER FOR TILTING MOVEMENT AOBUT AN AXIS DISPOSEDLONGITUDINALLY OF SAID CARRIAGE, AND A PERCUSSION TOOL SLIDABLY MOUNTEDIN SAID VERTICALLY DISPOSED GUIDEWAY FOR RECIPROCATORY IMPACINGOPERATION THEREIN, THE ARRANGE-